The present invention relates generally to systems and methods for detecting and/or transmitting images. More particularly, the present invention relates to detecting and transmitting images in relation to a cellular telephone.
Focusing lenses of mobile image capture devices, such as CMOS-based digital cameras, are often not telecentric. Telecentric lenses are often too bulky for portable devices. Hence, a principle ray of the light at each pixel of a sensor array is not normal to the surface of the pixel. Moreover, the further a pixel is from the center of the array, the greater the angle of the principle ray varies from normal.
Pixels typically include a light sensor (e.g., photodiode or the like), a microlens that focuses incoming light on the light sensor, and a color filter. Pixels also may include one or more silicon dioxide layers, silicon nitride layers, planarization layers, and the like. Hence, the stackup of layers, which may have different refractive indexes and different thicknesses, complicate the problem. Essentially, the light must be redirected down and into a hole formed by the pixel layers.
Additionally, pixels are not light sensing throughout. The light sensitive portion of a pixel may be only a fraction of the pixel's area. Even if a microlens is positioned to focus light fully within the pixel area, some of the light may fall off the light sensitive region, leading to loss of signal. Further, the light may be obscured by metal wiring and the like as the light travels through the pixel.
Complicating the foregoing is the reality that production equipment, such as mask lithography equipment, is not infinitely variable. The equipment typically has a finite tolerance that prevents exact location of mask borders.